1. Field of the Invention
The present invention relates to a chip package structure and manufacturing method thereof, and more specifically to a fingerprint sensor chip package structure and manufacturing method thereof.
2. Description of Related Art
Fingerprint sensor chip packages may be installed in a variety of electronic devices, such as smart phones, mobile phones, tablets, laptops, and personal digital assistants (PDA), to identify a user's fingerprint. Modern fingerprint sensor chip packaging may roughly be separated into the packaging with a flexible printed circuit board and the packaging with a rigid printed circuit board. The fingerprint sensor chip package structure with the flexible printed circuit board usually has the sensing circuits for identifying the user's fingerprint being disposed on the flexible printed circuit board, and the user processes the fingerprint identification by touching the sensing circuits located on the flexible printed circuit board. However, the signals in this package type are transmitted to the fingerprint sensor chip through the sensing circuits located on the flexible printed circuit board such that the reaction speed would be slower compared to the package type with the fingerprint identification undertaken directly on the fingerprint sensor chip.
The other common fingerprint sensor chip package structure mainly comprises a circuit carrier, a fingerprint sensor chip, a plurality of bonding wires, and an encapsulant. A sensing area for identifying the user's fingerprint is usually located on the active surface of the fingerprint sensor chip. The fingerprint sensor chip is normally bonded to the circuit carrier with its back surface, and electrically connected to the circuit carrier with the bonding wires coupling the active surface of the fingerprint sensor chip and the circuit carrier. Therefore, the encapsulant formed on the circuit carrier would cover the bonding wires and part of the fingerprint sensor chip, and expose the sensing area on the active surface of the fingerprint sensor chip. The loop height of the bonding wires restrains the decrease in the thickness of the encapsulant, causing difficulty in reduction of the overall thickness of the fingerprint sensor chip package structure. Moreover, since the user would repeatedly touch the sensing area, the bonding wires are likely to break off from the fingerprint sensor chip or the circuit carrier, thereby decreasing the sensing sensitivity of the fingerprint sensor chip package structure, or even leading to malfunction or damage. In addition, there are the upper metal layer and bond pads of the integrated circuits, and the passivation layer covering the upper metal layer disposed on the active surface of the fingerprint sensor chip. These protruding upper metal layer and bond pads make the active surface uneven. When the user touches the active surface with his or her finger, the uneven active surface is likely to cause the fingerprint identification difficult or to decrease the sensing sensitivity.